In response to Mark Jones' critical points of view concerning clicks
in hunting talk, I would like to express my own reflections on this
topic. The following is an excerpt of my conference contribution on
the topic:
According to the Modulation Theory (Traunm�ller, 94), speech arises
when speakers modulate their voice with conventional linguistic
gestures. The voice as such is still used for conveying paralinguistic
information about the speaker and his state and attitude. This is
characteristic of all human speech. However, voiceless fricatives and
clicks do not convey such paralinguistic information. Out of context,
they do not even identify themselves as human sounds. Listeners who
are not familiar with click languages tend to perceive the clicks as
extraneous noise even within the context of a stream of speech.
The property of fricatives and clicks not to disclose themselves as human
sounds appears to be exploited in cooperative hunting. Knight et al. (02
report: "During stalking of prey, Ju'hoansi revert to a hushed
whisper-like communication. The speech is devoiced and consists almost
entirely of clicks". Clicks are short in duration but more intense than
other speech sounds. They are easily audible to the prey as well as to the
hunters, but if the prey does not recognize them as produced by a predator,
their use is likely to positively impact hunting success. Thus, it may be
that the phonemic use of clicks originated in the context of hunting.
Subsequently, the use of clicks may have spread to other groups of hunters
who noticed their advantage. This advantage is quite independent of a
possible relationship between the groups and its recognition does not
require a high frequency or intimate nature of contacts between the groups,
although this condition was certainly fulfilled when the Bantu who migrated
into southern Africa adopted clicks.
However, we are still left with the question of why the phonemic use
of clicks did not arise elsewhere. Olle Engstrand, who had previously
sought a connection between the origin of clicks and labial-velars,
which also are used predominantly in Africa (Engstrand 97), drew my
attention to the possibility that an anatomical feature might be
responsible: Four of the five speakers of !X��, investigated by
Traill (85) had gently sloping palates without an alveolar
ridge. Traill quotes a study by van Reenen (64), according to which
this feature is widespread in the San population. This feature
reduces the amount of distortion of the tongue that is required in
producing clicks, especially for laminal clicks. It predisposes
speakers for the production of such clicks and thereby increases the
likelihood for clicks to acquire a function in speech. In order to
evaluate this hypothesis, it would be informative to know whether
gently sloping palates without an alveolar ridge are common also among
the Hadza and to what extent this trait was present in prehistoric
African populations and elsewhere.
For references consult "Clicks and the idea of a human protolanguage"
http://www.ling.umu.se/fonetik2003/pdf/001.pdf
(In the previous posting, there was an error in this URL)
Hartmut Traunm�ller

Dear All,
re-reading my post, I feel I should perhaps elaborate a little on my
'whispered-clicks' theory.
In whisper, the vocal folds do not vibrate and phonetic voicing is not
produced. This greatly reduces the amplitude of the speech signal,
though some voiceless sounds, like fricatives, are relatively
unaffected.
Clicks are produced using the velaric ingressive airstream mechanism,
which does not use the lungs. Consequently, no matter whether we
whisper or shout, clicks are essentially unaffected. They also have a
very high amplitude relative to other speech sounds.
A hunter who speaks a 'non-click' language can attempt to whisper to
other hunters, but once the distance between them has exceeded a few
feet, whispered speech will not be heard.
A 'clicking' hunter can whisper to others, and they will hear the
clicks even when the rest of the whisper is inaudible.
This means that, as long as the message contains enough clicks (as is
likely in most languages which possess linguistic clicks) with a
pattern which can be attributed relatively unamibiguously to canonical
speech, verbal communication can continue, even across relatively wide
distances.
So, clicks will appear to be used in hunting, but in fact, the hunters
are merely able to use whisper across greater distances. It is crucial
to realise that the use of clicks here would be a consequence of their
established use in everyday communication.
The questions to which answers are needed in this matter (I feel), are
whether or not the hunters are whispering to each other, and what
relationship obtains between the hunting use of clicks and everyday
usage (same lexical items, same phonological distribution etc.).
Of course, not being an expert in these languages or having heard the
data, I can't be sure from the comfort of my armchair in Cambridge,
but nevertheless it seems likely to me that the origin of linguistic
clicks must be sought elsewhere, not in hunting speech.
Roger Lass is right that click production is essentially the same
mechanism used for sucking, but in sucking the velum tends to be
lowered, and not all clicks are nasalised. Interestingly, many
non-clicking phonetics students (including me) seem able to produce
nasalised clicks before non-nasalised ones, and some click languages
have some degree of spontaneous nasalisation with their clicks
(e.g. Sandawe, Wright et al. 1995, UCLA Working papers in Phonetics
91: 1-24). Nasalised clicks also occur in the rendition of a Chinese
nursery rhyme (G. Nathan, 2001, Journal of the International Phonetic
Association 31(2): 223-229).
The Pacific language to which Roger refers is perhaps Damin, a
ceremonial language of the Lardil tribe of Mornington Island in
Australia. Here the clicks are egressive, not ingressive (Laver 1994,
Principles of Phonetics, Cambridge University Press, and others). My
own musings on egressive clicks suggest that they don't sound very
different from ingressive clicks, though they tend to be more
fricated, presumably due to the great pressures involved in their
production and the ineffectiveness of the seal provided by the lips
and tongue under these conditions, as well as tongue movement during
compression of the air.
Mark
Mark Jones
Department of Linguistics
University of Cambridge